All cult safehouse, hideout, and base missions have stopped generating completely. When I attempted to force one to appear by editing a save, I was given an error message saying the specified region did not exist. The same thing happened for the crop circles missions too. This was all on a clean save.
I have also encountered a similar error in an older save, this time affecting the Syndicate Lab mission. The save in question is attached.
Could there have been an error in the zone changes you've been making lately?
EDIT: Disregard, updating OXCE to newest version seems to have fixed it.